DIY_EFI Digest Tuesday, November 2 1999 Volume 04 : Number 618 In this issue: Re: non-DFI tach question Re: non-DFI tach question See the end of the digest for information on subscribing to the DIY_EFI or DIY_EFI-Digest mailing lists. ---------------------------------------------------------------------- Date: 03 Nov 99 01:48:52 +1200 From: "Tom Parker" Subject: Re: non-DFI tach question Unknown wrote: >drop of the ground when the points open. Could I use parts from a GM 4 >cylinder HEI coil ie: coil pickup and ignition module.I think I am headed >in the right direction just need some advice on different ways I could do >this. Anything that has 2 pulses per revolution (for four cyclinder four cycle tachometer) should do the trick. A cam and good old points even. >Ideally I would like to have a digital display which would allow me to >have a more realistic reading of rpm's as opposed to well it looks like it >is 2000 not 2010, 2020 or 2050. Any help would be greatly appreciated. And >sorry for taking up bandwidth for the non-dfi post but this was my last >place to ask . . . thanks in advance. Have a look at frequency to voltage converters. Don't know who makes them, but it shouldn't take long to find a datasheet. I'm not sure how accurate they can be, but you should be able to hook one up with a multimeter as a display, or use the movement in the tach if it is accurate enough. A friend of mine put such a circuit into his misbehaving period tach. Looks completely original from the outside, but reads far more accuratly. Also, someone else was wondering how to connect a 6 cyclinder tach to a 4 cyclinder engine (or the reverse). You could use a freq->volt and then a voltage to frequency (voltage controlled oscilator??) with an aproprate divider between them. Just a thought, no idea if it is feasable.. - -- Tom Parker - parkert@xxx.nz - http://www.geocities.com/MotorCity/Track/8381/ ------------------------------ Date: Tue, 2 Nov 1999 08:36:00 +0000 From: "Alex C. Peper" Subject: Re: non-DFI tach question Dynos use a tach generator. You could hook a small surplus one to shaft and read voltage. Also dynos use a shaft counter you can make one with a magnet and hall effect sensor from digi-key. Alex > Date: Mon, 1 Nov 1999 22:40:56 -0500 > From: brucep@xxx.net > Subject: non-DFI tach question > > I've searched high and low and haven't been able to find any info that was > of any use on this subject so I am turning to the "minds" of this group. > > I am building a steady state dyno and need to add a tach to it. I want to > measure the shaft speed of the dyno. (I don't want to read the engine > ignition) I can't afford a digital tach setup so I am looking to use a > analog 4 cylinder tach I have laying around till I can afford to upgrade. > What would be the easiest way to make this work? Does the tach sense the > drop of the ground when the points open. Could I use parts from a GM 4 > cylinder HEI coil ie: coil pickup and ignition module. I think I am headed > in the right direction just need some advice on different ways I could do > this. Ideally I would like to have a digital display which would allow me to > have a more realistic reading of rpm's as opposed to well it looks like it > is 2000 not 2010, 2020 or 2050. Any help would be greatly appreciated. And > sorry for taking up bandwidth for the non-dfi post but this was my last > place to ask . . . thanks in advance. > > Bruce ------------------------------ End of DIY_EFI Digest V4 #618 ***************************** To subscribe to DIY_EFI-Digest, send the command: subscribe diy_efi-digest in the body of a message to "Majordomo@xxx. A non-digest (direct mail) version of this list is also available; to subscribe to that instead, replace "diy_efi-digest" in the command above with "diy_efi".